This application claims the benefit of the Korean Application No. P2002-70809 filed on Nov. 14, 2002, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a device for putting polyethylene cladding on a galvanized steel plate, and more particularly, to a device for putting polyethylene cladding on a galvanized steel plate, in which polyethylene sheets are cladded on front and back surfaces of galvanized steel plate, which is mostly used for fabricating a steel pipe, for enhancing corrosion resistance, and durability.
2. Background of the Related Art
In general, the galvanized steel plate 1, having a zinc layer galvanized both on front and back surfaces of a steel plate, is widely used as a raw material of a steel pipe for sewage disposal because the galvanized zinc layers on front and back surfaces of the steel plate enhance corrosion resistance, and durability.
For reference, in formation of the steel pipe from the galvanized steel plate 1, the galvanized steel plate 1 is rolled into a helical form, with edges lock seamed, by a steel pipe former generally used in the field of a steel pipe industry, in which it can be known that if the galvanized steel plate 1 is corrugated before the rolling into the helical form by using an extra equipment, the finished steel pipe will be a corrugated steel pipe, which has a strength higher than non-corrugated steel pipe, with a longer durability.
In the meantime, currently, as demands for the steel pipe (inclusive of corrugate pipe) with better corrosion resistance, and durability formed of the galvanized steel pipe 1 is high for sewage disposal, the steel pipe is formed from polyethylene sheet 2 cladded galvanized steel plate, which is formed by putting polyethylene cladding on front and back surfaces of galvanized steel pipe, for improving the corrosion resistance, and durability.
Thus, the polyethylene clad galvanized steel plate requires putting the polyethylene cladding on front and back surfaces of the galvanized steel plate, for which on device is required. A related art process for putting polyethylene cladding on a galvanized steel plate will be explained.
In the related art, manual coating of an adhesive 3 on one surface of the galvanized steel plate 1, being unrolled from a roll, is made, and a roll of polyethylene sheet 2 is unrolled thereon, so that the polyethylene sheet 2 is pre-bonded on one surface of the galvanized steel plate 1.
Then, the galvanized steel plate 1 having the polyethylene sheet 2 pre-bonded on one surface thereof is turned over, manual coating of an adhesive on the other surface of the galvanized steel plate 1 is made, another roll of polyethylene sheet 2 is unrolled thereon, so that the polyethylene sheet 2 is pre-bonded on the other surface of the galvanized steel plate 1.
Referring to FIG 1, upon finishing the pre-bonding of the polyethylene sheets 2 on the one and the other surfaces of the galvanized steel plate 1, the polyethylene sheet 2 per-bonded galvanized steel plate 1 is passed through between compressive rollers with a plurality of rollers arranged oppositely, the pre-bonded polyethylene sheets 2 are bonded on the one surface and the other surface of the galvanized steel plate 1, with an adhesive layer formed inbetween, firmly and completely, to obtain a polyethylene clad galvanized steel plate 1, which may be used for forming a steel pipe.
In the meantime, in the process of bonding the polyethylene sheets 2 on both surfaces of the galvanized steel plate 1, the galvanized steel plate may be subjected to shot blasting for removing foreign matters from the one and the other surfaces, that improves adhesive capability of the polyethylene sheet 2 to the galvanized steel plate 1.
However, the related art process for putting polyethylene cladding on a galvanized steel plate has the following problems.
First, the putting of polyethylene cladding on a galvanized steel plate by bonding of an adhesive is liable to peel off as the bonding force between the galvanized steel plate 1 and the polyethylene sheet 2 becomes the weaker gradually as times goes by (particularly, in the case of corrugated polyethylene clad galvanized steel pipe), causing fast corrosion and short durability of the pipe.
Second, the non-automated process has a poor workability, with a low productivity and a high production cost.
Third, the poor washing of the galvanized steel plate 1 before bonding the polyethylene sheets 2 on both surfaces of the galvanized steel plate 1, such as one time of cleaning of the galvanized steel plate 1 surfaces with water, or no cleaning at all, failing to remove various impurities (particularly, organic impurities) from the both surfaces of the galvanized steel plate 1, can not, but cause peeling the polyethylene sheet 2 off the galvanized steel plate 1, that reduces the corrosion resistance, and durability. Even though, the galvanized steel plate 1 is subjected to shot blasting with steel pieces for perfect removal of the impurities in the invention of prevention of the peeling off in advance, the shot blasting results in damage to the zinc layer, that offsets the advantage of improvement of the bonding force, to some extent.
Fourth, uneven surfaces of the galvanized steel plate 1 which may be formed during initial rolling and/or unrolling for putting the polyethylene sheet 2 thereon caused by different reasons, that inevitably leads to bonding of the polyethylene sheet 2 on the uneven surfaces of the galvanized steel plate 1, with a poor bonding force, which affects bonding of adjacent parts, are liable to cause peeling of the polyethylene sheet 2 off the galvanized steel plate 1, that drops the corrosion resistance, and durability.
Accordingly, the present invention is directed to a device for putting polyethylene cladding on a galvanized steel plate that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a device for putting polyethylene cladding on a galvanized steel plate, in which putting of polyethylene cladding on both surfaces of a galvanized steel plate is automated by welding, thereby enhancing productivity by improving workability, and dropping a production cost by saving labor cost.
Another object of the present invention is to provide a device for putting a polyethylene cladding on a galvanized steel plate, in which various impurities are removed from a galvanized steel plate while giving no damage to the zinc layer before welding the polyethylene sheets on the galvanized steel plate, and uneven surfaces of the galvanized steel plate being unrolled from a roll are flattened, for preventing the polyethylene cladding from being peeled off the galvanized steel plate even if prolonged use of the steel pipe, thereby improving corrosion resistance, and durability.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the device for putting polyethylene cladding on a galvanized steel plate includes a base for placing different elements of the device thereon, an unroller at one end of the base for unrollably supporting a roll of galvanized steel plate, a plate press on one side of, and a distance away from the unroller on the base for pressing down unrolling galvanized steel plate to flatten uneven parts thereof, an ultrasonic cleaner on one side of, and a distance away from the plate press on the base for removing various impurities stuck to a surface of the galvanized steel plate passed through the plate press with an ultrasonic wave, a dryer on one side of, and a distance away from the ultrasonic cleaner on the base for drying moisture on the surface of the galvanized steel plate passed through the ultrasonic cleaner with high temperature dry air, an intermediate frequency heater on one side of, and a distance away from the dryer on the base for heating the galvanized steep plate passed through the dryer with an intermediate frequency wave, a sheet feeder on one side of, and a distance away from the intermediate frequency heater on the base having one pair of sheet unrollers each unrollably supporting a roll of polyethylene sheet, for bringing the polyethylene sheets unrolling from the sheet unrollers into contact with opposite sides of the galvanized steel plate, a roll press on one side of, and a distance away from the sheet feeder on the base for pressing down the polyethylene sheets in contact with opposite surfaces of the galvanized steel plate thereto, to weld thereto, a cooler on one side of, and a distance away from the roll press on the base for cooling down the galvanized steel plate having the polyethylene sheets welded on the opposite surfaces thereof, a sheet roller at the other end of the base, an opposite end of the unroller, for rolling the galvanized steel plate into a roll, a cutter between the cooler and the sheet roller on the base for cutting the galvanized steel plate as required, and a brake between the cutter and the sheet roller on the base for holding the galvanized steel plate at the moment the galvanized steel plate is cut with the cutter for preventing the galvanized steel plate rolled on the sheet roller from unrolling.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.